The general objective of this application is to develop and evaluate a new non-invasive clinical instrument that will measure wideband ear canal and middle ear power flow. By measuring the acoustic power flow into the cochlear, the conductive component of the peripheral auditory system may be characterized more accurately than in the past and improved diagnostic techniques could be developed using this instrument. The specific aims of this application are: 1. To demonstrate the feasibility of a clinically usable instrument by constructing a prototype. 2. To check the accuracy of the prototype using acoustic cavities with known impedance, and to compare its reliability and efficiency with current clinical instruments. 3. To evaluate the prototype in a clinical setting. Phase I of the project will consist of three stages. In Stage I, a prototype instrument will be designed and constructed. In Stage II, an independent laboratory will evaluate the accuracy of the prototype against known data and known instruments. Stage III will consist of a preliminary clinical evaluation of the instrument. Potential applications of the device include improved clinical methods for evaluating middle ear function, improved methods of measuring hearing sensitivity, particularly in infants and children, and in infants, children and adults with middle- ear pathologies, and improved hearing screening procedures using otoacoustic emissions. PROPOSED COMMERCIAL APPLICATION: The proposed instrument will provide important clinical information that cannot be obtained with existing audiological test instruments. Further, the instrument can also be used to improve substantially the efficiency and cost effectiveness of hearing screening programs using otoacoustic emissions.